First, you get on the list from the importers to get sent pictures of new mutations that are found in Africa. Then you get into a bidding contest with other large scaled breeders, bidding tens of thousands of dollars for the right to get that animal. Then you import it, acclimate it, and hope that it breeds, then hope that it's genetic. Then it's your line of XXX morph.
Or...you hit the ball python lottery like Justin Kobylka, you raise up a CH female, have a "feeling" about her and the markers that you see, and you breed her pastel son back to her, and you produce pastel pied, thus having your own line of pieds.